Printer having geared media pick-up roller

ABSTRACT

A printer is provided having a sheet media transport mechanism, a pick-up roller arranged to be rotated so as to contact and pick-up sheet media from a sheet media supply, and a gear assembly for communicating a driving force of a motor to the pick-up roller to rotate the pick-up roller. A first gear of the gear assembly is directly coupled with a second gear of the gear assembly which is concentric with the pick-up roller. The first gear is configured to disengage from the second gear substantially at the point of delivery of a leading edge of the picked sheet media to the sheet media transport mechanism so as to cease communication of the driving force of the motor to the pick-up roller.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No. 11/293,817 filed Dec. 5, 2005, all of which is herein incorporated by reference.

FIELD OF THE INVENTION

The present invention is related to a media pick-up device of a printer which is configured to accurately pick media from a media supply and deliver it to a media transport device of the printer.

CO-PENDING APPLICATIONS

The following applications have been filed by the Applicant with the present application:

7,445,311 7,452,052 7,455,383 7,448,724 7,441,864 7,438,371 7,465,017 7,441,862 7,654,636 7,458,659 7,455,376 7,465,033 7,452,055 7,470,002 11/293,833 7,475,963 7,448,735 7,465,042 7,448,739 7,438,399 11/293,794 7,467,853 7,461,922 7,465,020 11/293,830 7,461,910 11/293,828 7,270,494 7,632,032 7,475,961 7,547,088 7,611,239 11/293,819 11/293,818 11/293,816 7,469,990 7,441,882 7,556,364 7,357,496 7,467,863 7,431,440 7,431,443 7,527,353 7,524,023 7,513,603 7,467,852 7,465,045 The disclosures of these co-pending applications are incorporated herein by reference. The above applications have been identified by their filing docket number, which will be substituted with the corresponding application number, once assigned.

CROSS REFERENCES TO RELATED APPLICATIONS

Various methods, systems and apparatus relating to the present invention are disclosed in the following US patents/patent applications filed by the applicant or assignee of the present invention:

6,750,901 6,476,863 6,788,336 7,249,108 6,566,858 6,331,946 6,246,970 6,442,525 7,346,586 09/505,951 6,374,354 7,246,098 6,816,968 6,757,832 6,334,190 6,745,331 7,249,109 7,197,642 7,093,139 7,509,292 10/636,283 10/866,608 7,210,038 7,401,223 10/940,653 10/942,858 7,364,256 7,258,417 7,293,853 7,328,968 7,270,395 7,461,916 7,510,264 7,334,864 7,255,419 7,284,819 7,229,148 7,258,416 7,273,263 7,270,393 6,984,017 7,347,526 7,357,477 7,465,015 7,364,255 7,357,476 11/003,614 7,284,820 7,341,328 7,246,875 7,322,669 7,506,958 7,472,981 7,448,722 7,575,297 7,438,381 7,441,863 7,438,382 7,425,051 7,399,057 11/246,671 7,448,720 7,448,723 7,445,310 7,399,054 7,425,049 7,367,648 7,370,936 7,401,886 7,506,952 7,401,887 7,384,119 7,401,888 7,387,358 7,413,281 10/922,842 10/922,848 6,623,101 6,406,129 6,505,916 6,457,809 6,550,895 6,457,812 7,152,962 6,428,133 7,204,941 7,282,164 7,465,342 7,278,727 7,417,141 7,452,989 7,367,665 7,138,391 7,153,956 7,423,145 7,456,277 7,550,585 7,122,076 7,148,345 7,470,315 7,572,327 7,416,280 7,252,366 7,488,051 7,360,865 6,746,105 11/246,687 7,645,026 7,322,681 11/246,686 11/246,703 11/246,691 7,510,267 7,465,041 11/246,712 7,465,032 7,401,890 7,401,910 7,470,010 11/246,702 7,431,432 7,465,037 7,445,317 7,549,735 7,597,425 7,661,800 11/246,667 7,156,508 7,159,972 7,083,271 7,165,834 7,080,894 7,201,469 7,090,336 7,156,489 7,413,283 7,438,385 7,083,257 7,258,422 7,255,423 7,219,980 7,591,533 7,416,274 7,367,649 7,118,192 7,618,121 7,322,672 7,077,505 7,198,354 7,077,504 7,614,724 7,198,355 7,401,894 7,322,676 7,152,959 7,213,906 7,178,901 7,222,938 7,108,353 7,104,629 7,303,930 7,401,405 7,464,466 7,464,465 7,246,886 7,128,400 7,108,355 6,991,322 7,287,836 7,118,197 7,575,298 7,364,269 7,077,493 6,962,402 10/728,803 7,147,308 7,524,034 7,118,198 7,168,790 7,172,270 7,229,155 6,830,318 7,195,342 7,175,261 7,465,035 7,108,356 7,118,202 7,510,269 7,134,744 7,510,270 7,134,743 7,182,439 7,210,768 7,465,036 7,134,745 7,156,484 7,118,201 7,111,926 7,431,433 7,018,021 7,401,901 7,468,139 7,448,729 7,246,876 7,431,431 7,419,249 7,377,623 7,328,978 7,334,876 7,147,306 09/575,197 7,079,712 6,825,945 7,330,974 6,813,039 6,987,506 7,038,797 6,980,318 6,816,274 7,102,772 7,350,236 6,681,045 6,728,000 7,173,722 7,088,459 09/575,181 7,068,382 7,062,651 6,789,194 6,789,191 6,644,642 6,502,614 6,622,999 6,669,385 6,549,935 6,987,573 6,727,996 6,591,884 6,439,706 6,760,119 7,295,332 6,290,349 6,428,155 6,785,016 6,870,966 6,822,639 6,737,591 7,055,739 7,233,320 6,830,196 6,832,717 6,957,768 7,456,820 7,170,499 7,106,888 7,123,239 10/727,162 7,377,608 7,399,043 7,121,639 7,165,824 7,152,942 10/727,157 7,181,572 7,096,137 7,302,592 7,278,034 7,188,282 7,592,829 10/727,180 10/727,179 10/727,192 10/727,274 10/727,164 7,523,111 7,573,301 7,660,998 10/754,536 10/754,938 10/727,160 7,171,323 7,369,270 6,795,215 7,070,098 7,154,638 6,805,419 6,859,289 6,977,751 6,398,332 6,394,573 6,622,923 6,747,760 6,921,144 10/884,881 7,092,112 7,192,106 7,457,001 7,173,739 6,986,560 7,008,033 7,551,324 7,222,780 7,270,391 7,195,328 7,182,422 7,374,266 7,427,117 7,448,707 7,281,330 10/854,503 7,328,956 10/854,509 7,188,928 7,093,989 7,377,609 7,600,843 10/854,498 10/854,511 7,390,071 10/854,525 10/854,526 7,549,715 7,252,353 7,607,757 7,267,417 10/854,505 7,517,036 7,275,805 7,314,261 7,281,777 7,290,852 7,484,831 10/854,523 10/854,527 7,549,718 10/854,520 7,631,190 7,557,941 10/854,499 10/854,501 7,266,661 7,243,193 10/854,518 10/934,628 7,163,345 7,448,734 7,425,050 7,364,263 7,201,468 7,360,868 7,234,802 7,303,255 7,287,846 7,156,511 10/760,264 7,258,432 7,097,291 7,645,025 10/760,248 7,083,273 7,367,647 7,374,355 7,441,880 7,547,092 10/760,206 7,513,598 10/760,270 7,198,352 7,364,264 7,303,251 7,201,470 7,121,655 7,293,861 7,232,208 7,328,985 7,344,232 7,083,272 7,621,620 7,669,961 7,331,663 7,360,861 7,328,973 7,427,121 7,407,262 7,303,252 7,249,822 7,537,309 7,311,382 7,360,860 7,364,257 7,390,075 7,350,896 7,429,096 7,384,135 7,331,660 7,416,287 7,488,052 7,322,684 7,322,685 7,311,381 7,270,405 7,303,268 7,470,007 7,399,072 7,393,076 11/014,750 7,588,301 7,249,833 7,524,016 7,490,927 7,331,661 7,524,043 7,300,140 7,357,492 7,357,493 7,566,106 7,380,902 7,284,816 7,284,845 7,255,430 7,390,080 7,328,984 7,350,913 7,322,671 7,380,910 7,431,424 7,470,006 7,585,054 7,347,534 7,441,865 7,469,989 7,367,650

An application has been listed by its docket number. This will be replaced when application number is known. The disclosures of these applications and patents are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Conventional print media pick-up devices for printers are designed to “pick” print media, such as sheets of paper, from a supply and deliver it to the media transport mechanism of the printer. The manner in which these devices deliver the sheets to the transport mechanism is an important factor in ensuring successful and trouble free picking. This is because, the transport mechanism generally pulls the sheets faster than the pick-up device can deliver the sheets, resulting in a speed mismatch on different parts of the sheet.

SUMMARY OF THE INVENTION

The present invention provides a gear train for driving the pick-up roller in which one of the gears can be disengaged from the other gears, thereby allowing the pick-up roller to ‘free wheel’ upon delivery of the print media to the media transport mechanism. This free wheeling reduces the occurrence of speed spikes in the feed of the print media. Power efficiency and accurate delivery of the media is also enhanced by arranging the disengageable gear in the gear train as close to the pick-up roller as possible to reduce drag on the media by the free wheeling pick-up roller.

In a first aspect the present invention provides a printer comprising:

-   -   a sheet media transport mechanism for transporting sheet media         past a printhead;     -   a pick-up roller arranged to be rotated so as to contact and         pick-up sheet media from a supply of sheet media and deliver the         picked sheet media to the sheet media transport mechanism; and     -   a gear assembly for communicating a driving force of a motor to         the pick-up roller so as to rotate the pick-up roller,     -   wherein a first gear of the gear assembly is arranged to         disengage from a second gear of the gear assembly substantially         at the point of delivery of a leading edge of the picked sheet         media to the sheet media transport mechanism so as to cease         communication of the driving force of the motor to the pick-up         roller.

Optionally, the gear assembly is configured to rotate the pick-up roller at a rotational speed which delivers the sheet media to the sheet media transport mechanism at a first speed; the sheet media transport mechanism is configured to transport the sheet media at a second speed; and the first speed is lower than the second speed.

Optionally, the first speed is about 5% lower than the second speed.

Optionally, the gearing assembly is configured to deliver a gearing ratio of 50:1 from the motor to the pick-up roller.

Optionally, the motor is configured to deliver a maximum torque of 2 mNm.

Optionally, the first gear is configured to disengage from the second gear due to the increase in rotational speed of the pick-up roller at the point of delivery of the leading edge of the picked sheet media to the sheet media transport mechanism.

Optionally, the first gear is configured to re-engage with the second gear substantially at the point of a trailing edge of the picked sheet media leaving contact with the pick-up roller.

Optionally, the first gear is configured to re-engage with the second gear due to a driving force of the motor and the decrease in rotational speed of the pick-up roller at the point of the trailing edge of the picked sheet media leaving contact with the pick-up roller.

Optionally, the first gear is arranged so as to be pivotable relative to the second gear so as to disengage and re-engage therewith.

Optionally, the gear assembly incorporates a plurality of gears which cooperate with one another so as to communicate the rotation of a shaft of the motor to a shaft of the pick-up roller.

Optionally, the second gear is arranged on the shaft of the pick-up roller and the first gear is an intermediate gear between the second gear and a third gear of the gear assembly which is arranged on the shaft of the motor.

Optionally, the gear assembly comprises at least five gears, and the second and third gears are arranged to communicate with one another via the first gear and fourth and fifth gears of the gear assembly.

Optionally, a pivot arm connects a bearing shaft of the first gear and a bearing shaft of the fourth gear, the pivot arm being arranged to pivot the first gear out of mesh with the second gear.

Optionally, the motor, driven roller and gear assembly are incorporated in a pick-up device of the printer.

Optionally, the pick-up roller and gear assembly are incorporated in an arm of the pick-up device, the arm being arranged to position the pick-up roller on the sheet media, in use.

Optionally, the pick-up device is mounted to the printer so as to be pivotable relative to the supply of sheet media.

Optionally, the pick-up roller incorporates a grip material for gripping the sheet media.

Optionally, the grip material is rubber.

Optionally, the supply of sheet media is incorporated in a media cartridge which is removably engageable with the printer.

Optionally, the sheet media is 100 mm by 150 mm photo paper.

In a second aspect the present invention provides an inkjet printer comprising:

-   -   a media supply; and     -   a gripless driven roller and an idler roller arranged, in use,         to take-up the media therebetween from the media supply and feed         it past a printhead having a plurality of ink ejection nozzles         arranged to print on the media as it is fed past the nozzles,         the driven roller being rotatably driven so as to impart         translational motion to the media upon contact with the media,     -   wherein a contact surface of the gripless driven roller which         contacts the media is substantially plain.

Optionally, the driven roller is a plain shaft roller.

Optionally, the contact surface of the driven roller is incorporated in at least one tubular sleeve arranged about an elongate shaft.

Optionally, the idler roller is supported by a body of the printer so as to be moveable away from and toward the driven roller whilst maintaining a minimum gap between the driven and idler rollers, the idler roller being arranged to rotate due to the translational motion imparted to the media.

Optionally, the minimum gap between the driven and idler rollers is less than a thickness of the media, the movement of the idler roller being configured to allow the media to pass between, and contact, the contact surfaces of the driven and idler rollers.

Optionally, the minimum gap is about 200 microns and a thickness of the media is at least about 250 microns.

Optionally, the media is photo paper.

Optionally, the photo paper is 4 by 6 inch photo paper.

Optionally, the driven and idler rollers are configured to transport the 4 by 6 inch photo paper, and the pagewidth printhead is configured to print across a 4 by 6 inch pagewidth.

Optionally, the photo paper has a pagewidth of about 100 millimetres.

Optionally, the driven and idler rollers are configured to transport the 100 millimetre wide photo paper, and the pagewidth printhead is configured to print across the 100 millimetre pagewidth.

Optionally, the idler roller is biased towards the driven roller by a spring assembly mounted to the body, the spring constant of the spring assembly being configured so that the take-up of the media causes the movement of the idler roller away from the driven roller.

Optionally, the driven roller is rotatably driven by a motor mounted to a body of the printer.

Optionally, the driven roller is operationally connected to the motor via a pulley assembly.

Optionally, the pulley assembly incorporates a first pulley wheel arranged about one longitudinal end of the driven roller, a second pulley wheel arranged about a shaft of the motor and a belt arranged about the first and second pulley wheels.

Optionally, the belt is a smooth belt.

Optionally, the pulley assembly further incorporates a tensioner for tensioning the belt about the first and second pulley wheels.

Optionally, the printhead is incorporated in a printing cartridge which is removably engageable with the printer.

Optionally, the printhead is pagewidth printhead, a pagewidth being about 100 mm.

Optionally, the media supply is incorporated in a media cartridge which is removably engageable with the printer.

In a third aspect the present invention provides a printer comprising:

-   -   at least one elongate roller arranged, in use, to rotate so as         to transport print media within the printer;     -   a support frame for supporting the roller at the longitudinal         first and second ends of the roller so as to allow the rotation         of the roller; and     -   fixing means for fixing the roller to the support frame at the         first end of the roller, the fixing means comprising:         -   a bearing into which the first end of the roller is             positioned for allowing the rotation of the roller; and         -   engagement means arranged to slidably engage with the             support frame so as to fix the roller thereto, the bearing             being configured to allow pivotal movement of the elongate             roller about the second end of the roller during the sliding             engagement of the engagement means and support frame.

Optionally, the support frame has a slot through which the first end of the roller is able to pass so as to engage with the bearing of the fixing means, the slot being configured to allow movement of the first end during the sliding engagement of the engagement means and support frame.

Optionally, the movement of the first end during the sliding engagement moves the roller from being at an angle off normal to the transport path of the print media to being normal to the transport path; and the bearing is configured to accommodate the angular movement of the roller.

Optionally the bearing is configured to only contact the first end of the roller about a line around the circumference of the roller throughout the angular movement of the roller.

Optionally, a cross-section of the bearing contact face is triangular.

Optionally, the engagement means slidably engages with the support frame by sliding parallel to the transport path.

Optionally, the fixing means incorporates a plate having the bearing positioned in a hole therethrough, and the engagement means incorporates at least one tab provided on the plate, the tab being configured to slidably engage with a slot of the support frame.

In a further aspect there is provided a printer further comprising second fixing means for fixing the roller to the support frame at the second end of the roller, the second fixing means comprising:

-   -   a second bearing into which the second end of the roller is         positioned for allowing the rotation of the roller, the second         bearing being configured to allow the pivotal movement of the         elongate roller about the second end during the sliding         engagement of the engagement means and support frame.

Optionally, the second bearing is configured to accommodate the angular movement of the roller during the sliding engagement of the engagement means and support frame.

Optionally, the second bearing is configured to only contact the second end of the roller about a line around the circumference of the roller throughout the angular movement of the roller.

Optionally, a cross-section of the second bearing contact face is triangular.

Optionally, the second fixing means incorporates a plate having the second bearing positioned in a hole therethrough and at least one tab provided on the plate configured to engage with a slot of the support frame.

In a further aspect there is provided a printer comprising a plurality of elongate rollers for transporting the print media,

-   -   wherein the fixing means is arranged to fix each of the rollers         to the support frame at the first end of the rollers, the fixing         means comprising a plurality of the bearings with the first end         of each roller being positioned in a corresponding bearing.

Optionally, the bearing of the fixing means for one of the rollers is arranged to be movable with respect to the fixing means so that said roller is allowed to move with respect to the transport path; and

-   -   the fixing means comprises a spring for controlling the movement         of said bearing.

Optionally, the fixing means incorporates a plate and a hole assembly arranged on the plate in which said roller is supported, the hole assembly being movable with respect to the plate; said bearing is arranged on said roller; and the spring is arranged on the plate to act against the hole assembly.

In a further aspect there is provided a printer comprising a plurality of elongate rollers for transporting the print media,

-   -   wherein the first and second fixing means are arranged to fix         each of the rollers to the support frame at the respective first         and second ends of the rollers, the first and second fixing         means comprising a plurality of the first and second bearings         with the first and second ends of each roller being positioned         in a corresponding respective bearing.

Optionally, the first and second bearings for one of the rollers are arranged to be movable with respect to the respective first and second fixing means so that said roller is allowed to move with respect to the transport path; and the first and second fixing means comprise a spring for controlling the movement of said first and second bearings.

Optionally, the first and second fixing means each incorporate a plate and a hole assembly arranged on the plate in which said roller is supported, the hole assembly being movable with respect to the plate; said first and second bearings are arranged on said roller; and each spring is arranged on the respective plate to act against the respective hole assembly.

Optionally, the plurality of rollers are arranged, in use, to transport the print media past a pagewidth printhead, the printhead being incorporated in a printing cartridge which is removably engageable with the printer.

Optionally, the print media is supplied to the plurality of rollers from a media cartridge which is removably engageable with the printer.

In a fourth aspect the present invention provides a method of assembling a print media transport arrangement of a printer, the method comprising the steps of:

-   -   providing a support frame for at least one elongate roller;     -   positioning the roller so as to be supported at its longitudinal         first and second ends by the support frame;     -   positioning a bearing of a fixing plate about the first end of         the roller, the bearing being configured to allow rotation of         the roller, the rotation, in use, providing transport of print         media within the printer; and     -   slidably engaging the fixing plate with the support frame so as         to fix the roller thereto, wherein, during the sliding         engagement, the elongate roller pivots about the second end due         to the configuration of the bearing.

Optionally, in the step of positioning the roller, the first end of the roller is passed through a slot of the support frame, the slot being configured to allow movement of the first end during the engagement step.

Optionally, in the engagement step, the movement of the first end during the sliding engagement moves the roller from being at an angle off normal to the transport path of the print media to being normal to the transport path, the bearing being configured to accommodate the angular movement of the roller.

Optionally, the bearing is configured to only contact the first end of the roller about a line around the circumference of the roller throughout the angular movement of the roller in the engagement step.

Optionally, in the engagement step, the fixing plate is slid parallel to the transport path so as to slidably engage with the support frame.

Optionally, the fixing plate incorporates at least one tab configured to slidably engage with a slot of the support frame in the engagement step.

Optionally, in the step of positioning the roller so as to be supported at its longitudinal first and second ends by the support frame, the second end of the roller is positioned in a second bearing of a second fixing plate for fixing the second end of the roller to the support frame, the second bearing being configured to allow the rotation of the roller; and in the step of engaging the first fixing plate, the elongate roller pivots about the second end due to the configuration of both the first and second bearings.

Optionally, in the step of engaging the first fixing plate, the second bearing is configured to accommodate the angular movement of the roller.

Optionally, the second bearing is configured to only contact the second end of the roller about a line around the circumference of the roller throughout the angular movement of the roller in the step of engaging the first fixing plate.

Optionally, the step of positioning the roller comprises positioning a plurality of elongate rollers so as to be supported at their longitudinal first and second ends by the support frame; the step of positioning the bearing comprises positioning a plurality of bearings about the first end of each respective roller, each bearing being configured to allow rotation of the respective roller about the first end thereof; and in the engagement step, the configuration of each of the bearings allows the pivoting of the respective elongate roller about the second end thereof.

Optionally, the step of positioning the roller comprises positioning a plurality of elongate rollers so as to be supported at their longitudinal first ends by the support frame and positioned at their longitudinal second ends in a respective one of a plurality of second bearings of the second fixing plate, each second bearing being configured to allow rotation of the respective roller about the second end thereof; the step of positioning the first bearing of the first fixing plate comprises positioning a plurality of first bearings about the first end of each respective roller, each first bearing being configured to allow rotation of the respective roller about the first end thereof; and in the step of engaging the first fixing plate, the configuration of each of the bearings allows the pivoting of the respective elongate roller about the second end thereof.

In a fifth aspect the present invention provides an inkjet printer comprising:

-   -   an elongate shaft arranged, in use, to rotate so as to move a         capper for capping a pagewidth printhead out of and into its         capping position;     -   a support frame for supporting the shaft at the longitudinal         first and second ends of the shaft so as to allow the rotation         of the shaft; and     -   fixing means for fixing the shaft to the support frame at the         first end of the shaft, the fixing means comprising:         -   a bearing into which the first end of the shaft is             positioned for allowing the rotation of the shaft; and         -   engagement means arranged to slidably engage with the             support frame so as to fix the shaft thereto, the bearing             being configured to allow pivotal movement of the elongate             shaft about the second end of the shaft during the sliding             engagement of engagement means and support frame.

Optionally, the support frame has a slot through which the first end of the shaft is able to pass so as to engage with the bearing of the fixing means, the slot being configured to allow movement of the first end during the sliding engagement of the engagement means and support frame.

In a further aspect there is provided an inkjet printer wherein:

-   -   the movement of the first end during the sliding engagement         moves the shaft from being at an angle off parallel to the         capping position to being parallel to the capping position; and     -   the bearing is configured to accommodate the angular movement of         the shaft.

Optionally, the bearing is configured to only contact the first end of the shaft about a line around the circumference of the shaft throughout the angular movement of the shaft.

Optionally, a cross-section of the bearing contact face is triangular.

Optionally, the engagement means slidably engages with the support frame by sliding normal to the capping position.

Optionally, the fixing means incorporates a plate having the bearing positioned in a hole therethrough, and the engagement means incorporates at least one tab provided on the plate, the tab being configured to slidably engage with a slot of the support frame.

In a further aspect there is provided an inkjet printer, further comprising second fixing means for fixing the shaft to the support frame at the second end of the shaft, the second fixing means comprising:

-   -   a second bearing into which the second end of the shaft is         positioned for allowing the rotation of the shaft, the second         bearing being configured to allow the pivotal movement of the         elongate shaft about the second end during the sliding         engagement of the engagement means and support frame.

Optionally, the second bearing is configured to accommodate the angular movement of the shaft during the sliding engagement of the engagement means and support frame.

Optionally, the second bearing is configured to only contact the second end of the shaft about a line around the circumference of the shaft throughout the angular movement of the shaft.

Optionally, a cross-section of the second bearing contact face is triangular.

Optionally, the second fixing means incorporates a plate having the second bearing positioned in a hole therethrough and at least one tab provided on the plate configured to engage with a slot of the support frame.

Optionally, the second fixing plate incorporates a seat for housing a motor for driving the rotation of the shaft.

Optionally, a gear is arranged on the second end of the shaft, the seat of the second fixing plate being configured to arranged a motor gear of the motor in mesh with the shaft gear.

Optionally, the motor gear is a worm gear arranged on a shaft of the motor, the seat of the second fixing plate being configured so that the motor may be inserted into the seat by causing rotation of the shaft gear.

Optionally, the shaft gear is a part of a gearing assembly of the shaft for moving the capper.

Optionally, the printhead is incorporated in a printing cartridge which is removably engageable with the printer.

Optionally, the capper is incorporated in the printing cartridge.

Optionally, the printhead is pagewidth printhead and the capper is a pagewidth capper.

Optionally, a pagewidth is about 100 mm.

In a sixth aspect the present invention provides a method of assembling a capping mechanism of an inkjet printer, the method comprising the steps of:

-   -   providing a support frame for at least one elongate shaft;     -   positioning the shaft so as to be supported at its longitudinal         first and second ends by the support frame;     -   positioning a bearing of a fixing plate about the first end of         the shaft, the bearing being configured to allow rotation of the         shaft, the rotation providing transport of a capper out of, and         into, a capping position on a pagewidth printhead; and     -   slidably engaging the fixing plate with the support frame so as         to fix the shaft thereto, wherein, during the sliding         engagement, the elongate shaft pivots about the second end due         to the configuration of the bearing.

Optionally, in the step of positioning the shaft, the first end of the shaft is passed through a slot of the support frame, the slot being configured to allow movement of the first end during the engagement step.

Optionally, in the engagement step, the movement of the first end during the sliding engagement moves the shaft from being at an angle off parallel to the capping position to being parallel to the capping position, the bearing being configured to accommodate the angular movement of the shaft.

Optionally, the bearing is configured to only contact the first end of the shaft about a line around the circumference of the shaft throughout the angular movement of the shaft in the engagement step.

Optionally, in the engagement step, the fixing plate is slid normal to the capping position so as to slidably engage with the support frame.

Optionally, the fixing plate incorporates at least one tab configured to slidably engage with a slot of the support frame in the engagement step.

In a further aspect there is provided a method further comprising the steps of:

-   -   positioning a second bearing of a second fixing plate about the         second end of the shaft, the second bearing being configured to         allow the rotation of the shaft; and     -   slidably engaging the second fixing plate with the support frame         so as to fix the shaft thereto.

Optionally, in the step of engaging the first fixing plate, the second bearing is configured to accommodate the angular movement of the shaft.

Optionally, the second bearing is configured to only contact the second end of the shaft about a line around the circumference of the shaft throughout the angular movement of the shaft in the step of engaging the first fixing plate.

In a further aspect there is provided a method wherein:

-   -   the step of positioning the shaft comprises positioning a         plurality of elongate shafts so as to be supported at their         longitudinal first and second ends by the support frame;     -   the step of positioning the bearing comprises positioning a         plurality of bearings about the first end of each respective         shaft, each bearing being configured to allow rotation of the         respective shaft about the first end thereof; and     -   in the engagement step, the configuration of each of the         bearings allows the pivoting of the respective elongate shaft         about the second end thereof.

In a further aspect there is provided a method wherein:

-   -   the step of positioning the shaft comprises positioning a         plurality of elongate shafts so as to be supported at their         longitudinal first and second ends by the support frame;     -   the steps of positioning the first and second bearings of the         first and second fixing plates comprise positioning a plurality         of first and second bearings about the respective first and         second ends of each respective shaft, each bearing being         configured to allow rotation of the respective shaft about the         first and second ends thereof; and     -   in the step of engaging the first fixing plate, the         configuration of each of the bearings allows the pivoting of the         respective elongate shaft about the second end thereof.

In a seventh aspect the present invention provides an inkjet printer comprising:

-   -   a body;     -   a first gear assembly mounted to the body so as to cooperate         with a motor gear for driving rotation of the first gear         assembly, the first gear assembly having a code feature; and     -   a second gear assembly mounted to the body so as to cooperate         with the first gear assembly to be rotatable therewith, the         second gear assembly, in use, cooperating with a capper for         capping a printhead so that the rotation of the second gear         assembly moves the capper out of and into its capping position,     -   wherein the code feature of the first gear assembly is arranged         to cooperate with a holding feature of a mounting arrangement         used to mount the second gear assembly to the body, the code         feature being configured so that the cooperation with the         holding feature maintains the first gear assembly at a         predetermined position during the mounting of the second gear         assembly.

Optionally, the first gear assembly comprises first and second gears connected by a common shaft, the shaft being supported by the body to mount the first and second gears thereto, the first gear meshing with the motor gear and the second gear meshing with the second gear assembly.

Optionally, the first gear incorporates the code feature.

Optionally, the code feature is a protrusion arranged to protrude from part of the outer surface of the first gear with respect to the body.

Optionally, the protrusion has a semi-cylindrical shape.

Optionally, the second gear assembly comprises a third gear mounted to the body by a pin, the third gear meshing with the second gear of the first gear assembly.

Optionally, the third gear is an eccentric gear.

Optionally, the eccentric gear has an eccentricity feature configured to cooperate with an actuator feature of the capper, the cooperation causing the movement of the capper out of and into its capping position.

Optionally, the predetermined position of the first gear assembly is configured to position the eccentricity feature of the eccentric gear of the second gear assembly in a predetermined cooperation with the actuator feature of the capper.

Optionally, the eccentricity feature is a protrusion arranged to protrude from part of the outer surface of the eccentric gear with respect to the body.

Optionally, the protrusion has a semi-cylindrical shape.

Optionally, the eccentricity feature is configured to go into and out of cooperation with the actuator feature of the capper based on the rotated position of the eccentric gear in relation to the capper.

Optionally, the predetermined cooperation is configured to maintain the capper in its capping position.

In a further aspect there is provided an inkjet printer wherein:

-   -   the first gear assembly comprises two second gears connected by         the common shaft, both of the second gears meshing with the         second gear assembly; and     -   the second gear assembly comprises two third gears, both of the         third gears meshing with a respective second gear of the first         gear assembly.

Optionally, each of the third gears has an eccentricity feature configured to cooperate with a corresponding actuator feature of the capper, the cooperation causing the movement of the capper out of and into its capping position.

Optionally, the predetermined position of the first gear assembly is configured to position the eccentricity features of the third gears of the second gear assembly in a predetermined cooperation with the actuator features of the capper.

Optionally, each eccentricity feature is configured to go into and out of cooperation with the respective actuator feature of the capper based on the rotated position of the third gears in relation to the capper.

Optionally, the predetermined cooperation is configured to maintain the capper in its capping position.

Optionally, the printhead is incorporated in a printing cartridge which is removably engageable with the printer.

Optionally, the capper is incorporated in the printing cartridge.

In an eighth aspect the present invention provides a method of assembling a gear arrangement for a capper of an inkjet printer, the method comprising the steps of:

-   -   mounting a first gear assembly to the printer so as to cooperate         with a motor gear for driving rotation of the first gear         assembly, the first gear assembly having a code feature; and     -   mounting a second gear assembly the printer so as to cooperate         with the first gear assembly to be rotatable therewith, the         second gear assembly, in use, cooperating with a capper for         capping a printhead so that the rotation of the second gear         assembly moves the capper out of and into its capping position,     -   wherein in the step of mounting the second gear assembly the         code feature of the first gear assembly is arranged to cooperate         with a holding feature of a mounting arrangement used to mount         the second gear assembly to the printer, the code feature being         configured so that the cooperation with the holding feature         maintains the first gear assembly at a predetermined position         during the mounting of the second gear assembly.

Optionally, the step of mounting the first gear assembly comprises mounting a common shaft connecting first and second gears of the first gear assembly to the body so that the first gear meshes with the motor gear and the second gear meshes with the second gear assembly.

Optionally, the first gear incorporates the code feature.

Optionally, the step of mounting the second gear assembly comprises mounting a pin of a third gear of the second gear assembly to the body so that the third gear meshes with the second gear of the first gear assembly.

Optionally, the third gear has an eccentricity feature configured to cooperate with an actuator feature of the capper, the cooperation causing the movement of the capper out of and into its capping position.

Optionally, the predetermined position of the first gear assembly is configured to position the eccentricity feature of the third gear of the second gear assembly in a predetermined cooperation with the actuator feature of the capper.

Optionally, the eccentricity feature is configured to go into and out of cooperation with the actuator feature of the capper based on the rotated position of the third gear in relation to the capper.

Optionally, the predetermined cooperation is configured to maintain the capper in its capping position.

In a further aspect there is provided a method wherein:

-   -   wherein the step of mounting the first gear assembly comprises         mounting the common shaft connecting the first gear and two         second gears to the body so that each of the second gears mesh         with the second gear assembly; and     -   the step of mounting the second gear assembly comprises mounting         a pin of two third gears to the body so that each of the third         gears mesh with a respective one of the second gears of the         first gear assembly.

Optionally, each of the third gears has an eccentricity feature configured to cooperate with a corresponding actuator feature of the capper, the cooperation causing the movement of the capper out of and into its capping position.

Optionally, the predetermined position of the first gear assembly is configured to position the eccentricity features of the third gears of the second gear assembly in a predetermined cooperation with the actuator features of the capper.

Optionally, each eccentricity feature is configured to go into and out of cooperation with the respective actuator feature of the capper based on the rotated position of the third gears in relation to the capper.

Optionally, the predetermined cooperation is configured to maintain the capper in its capping position.

In a ninth aspect the present invention provides a printer comprising:

-   -   a support frame; and     -   a sheet media pick-up device pivotally mounted to the support         frame so as to be pivotable relative to a supply of sheet media,         the pick-up device comprising:         -   a driven roller arranged to be rotated so as to contact and             pick-up sheet media from the supply of sheet media and             deliver the picked sheet media to a sheet media transport             mechanism of the printer; and         -   a motor for rotatably driving the roller,     -   wherein the motor and driven roller are arranged to pivot with         the pick-up device, the pick-up device being configured to pivot         so that the driven roller is consistently positioned to contact         and pick-up the sheet media as the supply of sheet media is         successively depleted after each pick-up.

Optionally, the motor and driven roller are incorporated in a molded body of the pick-up device.

Optionally, the driven roller is incorporated in an arm of the molded body, the arm being arranged to position the driven roller on the sheet media, in use.

Optionally, the pick-up device further comprises a gear assembly which operationally connects the motor to the driven roller.

Optionally, the gear assembly incorporates a plurality of gears which cooperate with one another so as to communicate the rotation of a shaft of the motor to a shaft of the driven roller.

Optionally, the motor, driven roller and gear assembly are incorporated in a molded body of the pick-up device.

Optionally, the driven roller and gear assembly are incorporated in an arm of the molded body, the arm being arranged to position the driven roller on the sheet media, in use.

Optionally, the driven roller incorporates a grip material for gripping the sheet media.

Optionally, the grip material is rubber.

Optionally, the motor is configured to deliver a maximum torque of 2 mNm.

Optionally, the support frame is arranged to support the sheet media supply.

Optionally, the supply of sheet media is incorporated in a media cartridge, and the support frame is arranged to removably engage with the media cartridge.

Optionally, the driven roller is arranged to contact the sheet media through an opening in a lid of the media cartridge.

Optionally, the driven roller is configured to drive individual sheets up an inclined face of the media cartridge through the opening to the sheet media transport mechanism of the printer.

Optionally, the pick-up device is configured to pivot the driven roller out of contact with the sheet media when the leading edge of a picked sheet is delivered to, and taken-up by, the sheet media transport mechanism.

Optionally, the pick-up device is configured to swing about the pivot so as to position the driven roller back into contact with the sheet media, the swinging motion being configured to allow the driven roller to bounce on the sheet media when it comes back into contact therewith.

Optionally, the sheet media is 100 mm by 150 mm photo paper.

Optionally, the printer incorporating a pagewidth inkjet printhead for printing on the sheet media transported by the sheet media transport mechanism.

Optionally, the sheet media is 100 mm by 150 mm photo paper.

Optionally, a pagewidth is about 100 mm.

In a tenth aspect the present invention provides a method of picking sheet media in a printer, comprising:

-   -   contacting a pick-up roller with sheet media of a supply of         sheet media;     -   rotatably driving the pick-up roller with a motor via a gear         assembly so that the pick-up roller picks up the sheet media and         delivers the picked sheet media to a sheet media transport         mechanism for transporting sheet media past a printhead; and     -   substantially at the point of delivery of a leading edge of the         picked sheet media to the sheet media transport mechanism by the         pick-up roller, disengaging a first gear of the gear assembly         from a second gear of the gear assembly to cease the driving of         the pick-up roller.

Optionally, the driving of the pick-up roller rotates the pick-up roller at a rotational speed which delivers the sheet media to the sheet media transport mechanism at a first speed; the sheet media transport mechanism transports the sheet media at a second speed; and the first speed is lower than the second speed.

Optionally, the first speed is about 5% lower than the second speed.

Optionally, the gearing assembly is configured to deliver a gearing ratio of 50:1 from the motor to the pick-up roller.

Optionally, the motor is configured to deliver a maximum torque of 2 mNm.

Optionally, the disengaging of the first and second gears is caused by the increase in rotational speed of the pick-up roller at the point of delivery of the leading edge of the picked sheet media to the sheet media transport mechanism.

In a further aspect there is provided a method further comprising, substantially at the point of a trailing edge of the picked sheet media leaving contact with the pick-up roller, re-engaging the first and second gears.

Optionally, the re-engaging of the first and second gears is caused by a driving force of the motor and the decrease in rotational speed of the pick-up roller at the point of the trailing edge of the picked sheet media leaving contact with the pick-up roller.

Optionally, the second gear is arranged on the shaft of the pick-up roller and the first gear is an intermediate gear between the second gear and a third gear of the gear assembly which is arranged on a shaft of the motor.

Optionally, contacting the pick-up roller with the sheet media comprises allowing the pick-up roller to move relative to the supply of sheet media.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a perspective view of a cradle unit of a printer;

FIG. 2 shows a perspective view of the printer;

FIGS. 3A and 3B respectively show opposite side views of the cradle unit;

FIG. 4 illustrates an inserted state of a printhead cartridge in the cradle unit;

FIG. 5 shows an exploded view of the cradle unit and a media supply cartridge of the printer;

FIG. 6 shows a cross-sectional view of the printer taken along the line I-I of FIG. 2;

FIG. 7 shows a partial view illustrating a capper shaft supported by a support frame;

FIG. 8 illustrates assembly of a fixing plate onto the support frame;

FIGS. 9A and 9B respectively illustrate the fixing plate without and with a spring fitted;

FIGS. 10A and 10B illustrate assembly of media transport rollers into the support frame;

FIG. 11 illustrates assembly of a second fixing plate onto the support frame;

FIGS. 12A and 12B respectively illustrate the second fixing plate without and with a spring fitted;

FIG. 13A illustrates a conventional bearing arrangement for a roller shaft;

FIG. 13B illustrates a bearing arrangement of the fixing plates;

FIGS. 14A and 14B illustrate assembly of a coded gear on the capper shaft;

FIG. 15 shows a perspective view of the support frame within a jig and illustrates a holding arrangement for the coded gear;

FIGS. 16 and 17 illustrate respective operational positions of the jig;

FIG. 18 shows a perspective view of a motor for driving rotation of the capper shaft;

FIG. 19 shows a cross-sectional view of an operational arrangement of capping gears with actuator features of a capper of the printhead cartridge;

FIGS. 20A and 20B respectively illustrate the positions of the coded gear, one of the capping gears and associated actuator feature during operation of the capper;

FIG. 21 illustrates insertion of a printhead cartridge support in the support frame;

FIG. 22 illustrates a media sensor of a print media guide;

FIG. 23 shows a perspective view of a media transport drive arrangement mounted on the support frame;

FIG. 24 shows a perspective view of a media pick-up device mounted on the support frame;

FIGS. 25A and 25B illustrate assembly of the media pick-up device;

FIGS. 26A and 26B illustrate a disengageable gear assembly of the pick-up device;

FIG. 27 shows a perspective view illustrating the mounting of a connection interface;

FIG. 28 shows a perspective view illustrating the mounted connection interface;

FIG. 29 shows a perspective view illustrating the mounting of print control circuitry;

FIG. 30 illustrates various connections of the mounted print control circuitry;

FIG. 31 shows a system diagram of the printer;

FIG. 32 illustrates an exemplary power regulation and storage circuit;

FIG. 33 shows a perspective view illustrating mounting of a key feature;

FIG. 34 shows a perspective view illustrating the mounted key feature; and

FIG. 35 shows a perspective view of the media supply cartridge.

DETAILED DESCRIPTION OF EMBODIMENTS

A printer 100 is variously illustrated in the accompanying drawings. The printer 100 is intended for use as a digital photo color printer and is dimensioned to print 100 millimetre by 150 millimetre (4 inch by 6 inch) photos whilst being compact in size and light in weight. As will become apparent from the following detailed description, reconfiguration and dimensioning of the printer could be carried out so as to provide for other printing purposes.

The printer 100 of the illustrated photo printer embodiment has dimensions of 18.6 cm (W); 7.6 cm (H); 16.3 cm (D), and a weight of less than two Kilograms. The compact and lightweight design of the printer provides portability and ease of use.

The printer 100 may be easily connected to a PC via a USB connector 408 (such as a USB 1.1 port for USB 2.0 compatible PCs) and to digital cameras and other digital photo equipment, such as electronic photo albums and cellular telephones, via USB or a PictBridge connector 410. Direct printing is available when using Pictbridge compatible digital photo equipment. This enables quick and convenient printing of digital photo images.

Connection to external power is used, preferably to mains power via a 12 Volt; 2 Amp (or 24 Volt; 1 Amp) DC power converter at power connector 406. However, the printer may be configured to operate from an internal power source, such as batteries. The printer is configured to efficiently use power, operating with a maximum power consumption of 36 Watts.

The printer 100 has three core components: a printhead cartridge 200 housing a printhead and ink supply; a printer or cradle unit 400 for supporting the printhead cartridge and housing a media transport mechanism for transporting print media past the printhead; and a media supply cartridge 600 for supplying the media to the printer.

The following detailed description is direct to the cradle unit 400 and media supply cartridge 600, and therefore detailed description of the printhead cartridge is not provided herein. A full description of a suitable printhead cartridge for use with the cradle unit 400 is described in the Applicant's simultaneously co-filed U.S. patent application Ser. Nos. 11/293,804 (Docket No. RKA001US), 11/293,840 (Docket No. RKA002US), 11/293,803 (Docket No. RKA003US), 11/293,833 (Docket No. RKA004US, 11/293,834 (Docket No. RKA005US), 11/293,835 (Docket No. RKA006US), 11/293,836 (Docket No. RKA007US), 11/293,837 (Docket No. RKA008US), 11/293,792 (Docket No. RKA009US), the entire contents of which are hereby incorporated by reference. For ease of understanding, a brief excerpt of the description provided in these co-pending Applications is provided below under the heading Printhead Cartridge.

Printhead Cartridge

The printhead cartridge 200 is an assembly having the necessary components for operation as a printer when mounted to the printer or cradle unit having a media supply.

The printhead cartridge has a body which is shaped to fit securely in a complementarily shaped printhead cartridge support bay of the cradle unit (see FIG. 6). The body of printhead cartridge houses a printhead and an ink supply for supplying ink to the printhead and has a capper for capping the printhead when the printhead is not in use mounted thereto. A media path is formed between the printhead and the capper for the transport of print media past the printhead by the media transport mechanism of the cradle unit when the capper is not capping the printhead.

The printhead is a pagewidth inkjet printhead. By using a pagewidth printhead it is unnecessary to scan the printhead across print media, rather the printhead remains stationary with the print media being transported therepast for printing. By operating the printhead to continuously print as the print media is continuously fed past the printhead, so called ‘printing-on-the-fly’, the need to stall the media feed for each print line is obviated, therefore speeding up the printing performed.

The printer incorporating the printhead of the printhead cartridge is configured to print a full colour page, e.g., one 4 inch by 6 inch photo, in at most two seconds. In other words, the printhead is capable of printing at a minimum of 30 pages per minute up to 60 pages per minute. This high speed printing is performed at high quality as well, with a resolution of at least 1600 dots per inch being provided by the printhead. Such a high resolution provides true photographic quality above the limit of the human visual system.

This is achieved by forming the printhead from thousands of ink ejection nozzles across the pagewidth, e.g., about 100 millimetres for 4 inch by 6 inch photo paper. In the illustrated embodiment, the printhead incorporates 32,000 nozzles. The nozzles are preferably formed as Memjet™ or microelectomechanical inkjet nozzles developed by the Applicant. Suitable versions of the Memjet™ nozzles are the subject of a number of the applicant's patent and pending patent applications, the contents of which is incorporated herein by cross reference and the details of which are provided in the cross reference table above.

Brief detail of a printhead suitable for use in the printhead cartridge is now provided. The printhead is formed as a ‘linking printhead’ which comprises a series of individual printhead integrated circuits (ICs). A full description of the linking printhead, its control and the distribution of ink thereto is provided in the Applicant's co-pending U.S. application Ser. Nos. 11/014,769 (Docket No. RRC001US), 11/014,729 (Docket No. RRC002US), 11/014,743 (Docket No. RRC003US), 11/014,733 (Docket No. RRC004US), 11/014,754 (Docket No. RRC005US), 11/014,755 (Docket No. RRC006US), 11/014,765 (Docket No. RRC007US), 11/014,766 (Docket No. RRC008US), 11/014,740 (Docket No. RRC009US), 11/014,720 (Docket No. RRC010US), 11/014,753 (Docket No. RRC011US), 11/014,752 (Docket No. RRC012US), 11/014,744 (Docket No. RRC013US), 11/014,741 (Docket No. RRC014US), 11/014,768 (Docket No. RRC015US), 11/014,767 (Docket No. RRC016US), 11/014,718 (Docket No. RRC017US), 11/014,717 (Docket No. RRC018US), 11/014,716 (Docket No. RRC019US), 11/014,732 (Docket No. RRC020US) and 11/014,742 (Docket No. RRC021US), all filed Dec. 20, 2004 and U.S. application Ser. Nos. 11/097,268 (Docket No. RRC022US), 11/097,185 (Docket No. RRC023US), 11/097,184 (Docket No. RRC024US), all filed Apr. 4, 2005 and the entire contents of which are incorporated herein by reference. In the illustrated embodiment, the linking printhead has five printhead ICs arranged in series to create a printing zone of a 100.9 millimetre pagewidth (which is approximately four inches).

Each printhead IC incorporates a plurality of nozzles positioned in rows (see FIG. 7). The nozzle rows correspond to associated ink colours to be ejected by the nozzles in that row. The illustrated embodiment has ten such rows arranged in groups of two adjacent rows for five colour channels. However, other arrangements may be used. In this arrangement, each printhead IC has 640 nozzle per row, 1280 nozzles per colour channel, 6400 nozzles per IC and therefore 32000 nozzles for the five ICs of the printhead.

The nozzles are arranged in terms of unit cells containing one nozzle and its associated wafer space. In order to provide the print resolution of 1600 dots per inch, an ink dot pitch (DP) of 15.875 microns is required. By setting each unit cell to have dimensions of twice the dot pitch wide by five times the dot pitch high and arranging the unit cells in a staggered fashion as illustrated in FIG. 8, this print resolution is achieved.

Due to this necessary staggered arrangement of the nozzles discontinuity is created at the interface between the adjacent printhead ICs. Such discontinuity will result in discontinuity in the printed product causing a reduction in print quality. Compensation of this discontinuity is provided by arranging a triangle of nozzle unit cells displaced by 10 dot pitches at the interface of each adjacent pair of printhead ICs, as illustrated in FIG. 9. This nozzle triangle allows the adjoining printhead ICs to be overlapped which allows continuous horizontal spacing between dots across the multiple printhead ICs along the printhead and therefore compensates for any discontinuity. The vertical offset of the nozzle triangle is accounted for by delaying the data for the nozzles in the nozzle triangle by 10 row times. The serially arranged nozzles rows and nozzle triangles of the printhead ICs together make up the printing zone of the printhead.

The printhead cartridge may be operated either in a page-limited mode which sets the number of pages which can be printed using the printhead cartridge (e.g., 200 photo pages) or an ink-limited mode which sets a maximum number of pages that can be printed without depleting the ink of the (non-refillable) ink supply. In this way, the printhead cartridge is caused to be operational within the operational lifetime of the printhead nozzles and within the supply of ink for full colour printing. Other suitable modes for ensuring consistent print quality may also be used.

The arrangement and operation the capper is described in the Applicant's co-pending U.S. patent application Ser. Nos. 11/246,676 (Docket No. FND001US), 11/246,677 (Docket No. FND002US), 11/246,678 (Docket No. FND003US), 11/246,679 (Docket No. FND004US), 11/246,680 (Docket No. FND005US), 11/246,681 (Docket No. FND006US), and 11/246,714 (Docket No. FND007US), all filed Oct. 11, 2005 and the entire contents of which are hereby incorporated by reference.

For ease of understanding, a brief excerpt of the description provided in these co-pending applications is now provided. As illustrated in FIG. 19, the capper 202 of the printhead cartridge 200 has an elongate cap 204 which is biased by springs 206 into its capping position on the printhead. The cap 204 has lugs or actuation features 208 protruding from each longitudinal end which are used to move the cap into and out of its capping position.

In the capping position, the contact surface of the pad, which defines the capping zone, sealingly engages with the nozzles of the printhead thereby capping or covering the nozzles. This capping isolates the ink within the nozzles from the exterior, thereby preventing evaporation of water from the primed ink from the nozzles and the exposure of the nozzles to potentially fouling particulate matter during non-operation of the printhead. In the non-capping position, the contact surface is disengaged from the nozzles, allowing printing to be performed.

The manner in which the capper 202 is operated in cooperation with the cradle unit 400 when the printhead cartridge 200 is mounted to the cradle unit 400 is described in detail later.

Cradle Unit

The printer or cradle unit 400 is an assembly having the necessary components for operation as a printer when the printhead and media supply cartridges are mounted.

From the exterior, the cradle unit 400 has a body 402 and a lid 404 hinged to the body 402. The body 402 houses the power connector 406, the data (USB and PictBridge) connectors 408 and 410, a media supply cartridge slot 412, a printed media exit slot 414, which is normally covered with a pivotable flap 416, and a control panel 418.

With the lid 404 hinged in its open position, a levered frame 420 is exposed. The open position of the levered frame 420 allows access to a printhead cartridge support bay 422 for insertion and extraction of the printhead cartridge 200. The closed position of the levered frame 420, via a snap fit of a clip 424 with a release detail 426 of the body 402, secures an inserted printhead cartridge in operational position.

The printhead cartridge support bay 422 and release detail 426 are part of an upper portion 428 of the body 402 which cooperates with a lower portion 430. The cooperation of the upper and lower portion 430s, which are preferably plastic moldings, creates an outer shell of the body 402 used to house the internal components of the cradle unit 400.

The internal components are shown in exploded and cross-sectional views in FIGS. 5 and 6. For ease of understanding, the following description of the internal components of the cradle unit 400 and their relationship with the body 402 and printhead and media supply cartridges is made in terms of their assembly to form the cradle unit 400.

An elongate capper shaft 432 is inserted at either end into a support frame 434 by feeding the ends through slots or apertures 436 arranged on opposite sidewalls 434 a of the support frame 434. The sidewalls 434 a of the support frame 434 are joined by a base 434 b. The capper shaft 432 has a gear 438 fitted at either end which form part of a gearing assembly for operating the capper of the printhead cartridge.

A first end of the capper shaft 432 is fixed in place by a fixing plate 440 which is mounted to the support frame 434 as illustrated in FIG. 8. The fixing plate 440 has a number of tabs or hook features 442 (six are shown in FIGS. 8 and 9A) and a roller or ring bearing 444 for locating the first end of the capper shaft 432. The bearing aperture is arranged to align with the apertures 436 of the support frame 434 through which the capper shaft 432 projects. The bearing 444 is configured to allow the capper shaft 432 to rotate.

To assemble, the hook features 442, which have an “L” shaped profile as can be seen in FIG. 9A, are engaged with slots 446 in the support frame 434 whilst ensuring that the first end of the capper shaft 432 locates in the bearing aperture. The hook features 442 are configured to flex snap within the slots 446 so as to secure the fixing plate 440 to the support frame 434 by sliding of the hook features 442 within the slots 446. In this way, first end of the capper shaft 432 is fixed to the support frame 434. In the present embodiment, the hook features 442 are configured so that the fixing plate 440 is slid two millimetres before being secured, as shown by the arrow in FIG. 8. Additional securement of the fixing plate 440 may be provided by suitable means, such as screws.

The fixing plate 440 has a locator 448 for an elongate idler roller 450 and further roller or ring bearings 452 for locating an elongate entry or drive roller 454 and an elongate exit roller 456. The drive, idler and exit rollers are part of a media transport mechanism of the cradle unit 400. The rollers are assembled into the support frame 434 by passing them through associated apertures 458 in the sidewalls 434 a of the support frame 434 and then into the locator 448 and bearings 452, which are aligned with the support frame apertures 458, as illustrated in FIG. 10A. The rollers are thereby fixed at their first ends to the support frame 434 by the fixing plate 440, as illustrated in FIG. 10B.

The idler roller 450 has its own bearings on the roller shaft at either end, which locate within the locator 448 so that the idler roller 450 can rotate. The bearings 452 of the fixing plate 440 are also configured so that the drive and exit roller 454,456 can rotate. Suitable thrust washers and the like may also be used on the rollers to facilitate location and rotation.

The second ends of each of the capper shaft 432 and drive, idler and exit rollers 454,450,456 are fixed to the opposite sidewall 434 a of the support frame 434 by a second fixing plate 460. As with the first fixing plate 440, the second fixing plate 460 has a number of “L” shaped hook features 442 (six are shown in FIGS. 11 and 12A) which are engaged with slots 446 in the support frame 434 to flex snap therein by sliding of the hook features 442 within the slots 446, as shown by the arrow in FIG. 11.

Further, as with the first fixing plate 440, the second fixing plate 460 has roller bearings 444 and 452 for locating the second ends of the respective capper shaft 432, drive roller 454 and exit roller 456 and a locator 448 for locating the bearing on the second end of the idler roller 450 (as illustrated in FIG. 11). Again, the bearing apertures are arranged to align with the apertures of the support frame 434 through which the capper shaft 432 and rollers 454,456 project and the bearings 444,452 are configured to allow the capper shaft and rollers to rotate.

The locators 448 of the fixing plates 440,460 for supporting the idler roller 450 shaft are illustrated in FIGS. 9A, 9B, 12A and 12C. As can be seen from these drawings, the locators 448 are each formed as an arm 462 which projects from a flexible pivot point 464 into a slot 466 formed in the fixing plates 440,460. The idler roller 450 shaft locates in a hole 468 in the arms 462. Springs 470 locate on protrusions 472 on the arms 462 so as to be compressed and held between the arms 462 and protrusions 474 on the fixing plates 440,460. The springs 470 allow the idler roller 450 to move relative to the drive roller 454, which is located beneath the idler roller 450 as seen in the drawings. The range of movement is controlled by the springs 470 which ensures that the idler roller 450 returns to its stationary position. This stationary position sets a minimum gap between the drive and idler rollers and the movement facilitates the transport of media between the drive and idler rollers.

In particular, the minimum gap is set to be less than the thickness of the print media which is to be transported by the drive and idler rollers. In the present embodiment, the minimum gap is set to be about 200 microns when photo paper having a thickness of at least 250 microns is used. Media of other thicknesses could be used, and therefore other suitable minimum gaps set.

The sprung movement of the idler roller 450 away from the drive roller 454 allows the media to pass therebetween whilst being contacted by both the drive and idler rollers as the drive roller is rotationally driven (described in detail later). This ‘pinch’ of the rollers 450 and 454 on the media ensures that appropriate friction is imparted on the media for trouble-free and effective transport.

In the present embodiment, the drive roller 454 is provided as a plain shaft roller having a substantially gripless surface. That is, the plain shaft is not provided with a grip or grit surface or other friction providing surface. The Applicant has found that, surprisingly, the effective pinch of the rollers is retained in the printer 100 when such a gripless drive roller 454 is used. A gripless idler roller may also be used. In the illustrated embodiment, the drive roller 454 has a smooth surfaced tubular sleeve 476 (two are illustrated in the drawings) arranged on a shaft. The tubular sleeve may be, for example, formed from smooth plastic or rubber.

As can be seen from FIG. 6, the path of the media from the pinch of the drive and idler rollers 450,454 to the exit roller 456 past the inserted printhead is a substantially straight path. By configuring the printing path in this way, high printing speeds and quality are supported.

The fixing plates 440,460 are preferably plastic moldings with each of the hook features 442, locators 448, arms 462, protrusions 474 and bearing apertures formed as part of the molding. The support frame 434 is preferably press formed from metal to form the illustrated chassis.

The bearings 444,452 of the fixing plates 440,460 are configured to allow pivotal movement of the capper shaft 432 and rollers 450,454,456 during assembly. This pivotal movement is needed due to the angular mismatch between the first and second ends of the capper shaft 432 and rollers 454,456 when they are positioned in the mounted first fixing plate 440 and yet to be mounted second fixing plate 460. This angular movement of the rigid shaft and rollers is required so that potentially damaging stresses are not placed on the shafts, rollers, bearings and/or support frame. In the final mounted position, the configuration of the bearings 444,452 align the capper shaft 432 parallel to the capper and align the rollers 454,456 perpendicular to the transport direction of print media.

Conventional roller or ring bearings for a shaft/roller are illustrated in FIG. 13A. As can be seen, due to the flat face of the bearing mount the range of angular movement of a shaft/roller held by the bearings is very limited.

The bearing mount or contact face 478 of the roller bearings 444,452 of the present invention has an angular or triangular face with respect to the capper shaft 432 and rollers 454,456. As such, a relatively wide range of angular movement of the capper shaft and rollers, characterised by pivotal movement about the first end of the capper shaft and rollers as illustrated by the solid and dashed depictions in FIG. 13B, is made possible.

Other suitably configured bearing mounts or contact faces may also be used, so long as the required range of angular displacement of the capper shaft 432 and rollers 454,456 is accommodated. The range of angular displacement to be accommodated may be of the order of about one or two degrees. The sprung locators 448 of the fixing plates 440,460 similarly provide for the angular movement of the idler roller 450 during assembly.

Further, the slots/apertures 436,458 of the support frame 434 are configured so as to accommodate the linear movement of the capper shaft and roller ends during assembly. The additional space provided within the slots/apertures does not cause any unwanted movement of the capper shaft and rollers once assembled due to the rigid capture of the capper shaft and rollers by the fixing plates 440,460.

With the capper shaft 432 held in position to the support frame 434 by the fixing plates 440,460, a third gear 480 of the gearing assembly is fitted to the second end of the capper shaft 432 at the exterior of the fixing plate sidewall, as illustrated in FIGS. 14A and 14B. The gear 480 is arranged to communicate with a motor 482 for driving rotation of the capper shaft 432 (discussed later).

The gear 480 is provided with a code feature 484 formed as a protrusion from the outer surface of the gear with respect to the gear's teeth. In the illustrated embodiment, the code feature protrusion has as a half-cylindrical shape, however, other types of protrusions may be used. Preferably, the gear and protrusion are formed as a molding.

The code feature 484 is arranged to cooperate with a holding feature 486 of a jig or mounting arrangement 488 used in the next stage of assembly. As illustrated in the magnified portion of FIG. 15, the holding feature 486 comprises a slider block 490 which is slid into position about the code feature 484. In this way, uncontrolled rotation of the capper shaft 432 is eliminated during this assembly stage. Such rotation is unwanted due to the need to maintain correct capping timing in order to ensure correct and efficient operation of the capper.

The jig 488 is used to mount further gears of the gearing assembly of the capping mechanism to the support frame 434. The further gears are eccentric gears 492 having an eccentricity or cam feature 494, as illustrated in FIGS. 17 and 19. The eccentric gears 492 are positioned on associated retaining pins 496 on plungers 498 arranged on an arm 500 of the jig 488. The jig arm 500 is pivoted down to and locked at a mounting position for the eccentric gears 492 (see FIG. 16). The plungers 498 are then used to locate the eccentric gears 492 via the retaining pins 496 in apertured features 502 of the fixing plates 440,460 adjacent the bearing apertures for the capper shaft 432 (see FIG. 17). The retaining pins 496 are then held in place by suitable clips 504, such as “E” clips, which are positioned on the pins at the exterior of the support frame sidewalls 434 a,434 b whilst the jig 488 is in place (FIG. 18 illustrates one of the clips in place). The eccentric gears 492 are provided with bearings to freely rotate about the retaining pins.

During the location of the eccentric gears 492, the teeth thereof mesh with the teeth of the gears 438 positioned on the capper shaft 432, where this meshing is used to transfer rotation of the shaft gears 438 to the eccentric gears 492. Without the engagement of the code and holding features, this meshing may cause the aforementioned uncontrolled rotation of the capper shaft 432, placing the eccentric gears 492 in an unknown position.

Once the eccentric gears are clipped in place, the assembly is removed from the jig. Whilst the illustrated embodiment uses the jig to mount the eccentric gears to the support frame, some other means of mounting the eccentric gears, including by picker robot or hand, is possible, so long as a holding feature is provided to engage and hold the code feature of the coded gear during mounting.

The motor 482 for driving the capping shaft 432, and in turn the eccentric gears 492, is fitted into a seat 506 formed in the second fixing plate 460, as illustrated in FIG. 18. A worm gear 508 located on a shaft of the motor 482 is meshed with the coded gear 480 of the capper shaft 432, in order to transfer motor force to the capper shaft.

Some rotation of the coded gear occurs during the meshing of the coded and motor gears. However, as the position of the eccentric gears is known this rotation can be corrected at power up of the printer to correctly position the eccentricity features of the eccentric gears (discussed later).

The eccentricity feature 494 of each eccentric gear 492 is formed as a protrusion from the outer surface of the eccentric gear with respect to the eccentric gear's teeth. In the illustrated embodiment, the eccentricity feature protrusion has as a semi-cylindrical shape, however, other types of protrusions may be used. Preferably, the eccentric gears and protrusions are formed as a molding.

The eccentricity features 494 are used to operate the capper of the printhead cartridge 200. In the normal position of the eccentric gears 492, the eccentricity features 494 are positioned so that an open part 494 a of the eccentricity features 494 faces towards the position of the capper when the printhead cartridge 200 is inserted into the cradle unit 400 (see FIG. 6). In this way, the lugs 208 on the capper 202 locate within the eccentricity features 494, as illustrated in FIGS. 19 and 20A. In this arrangement, the cap 204 of the capper 202 is positioned against the printhead.

When it is desired to print, the motor 482 is operated to rotate the capper shaft 432 via the coded gear 480. This causes rotation of the eccentric gears 492 via the shaft gears 438. The gear train of the capping mechanism provides a gearing ratio of 40:1 at the capper. The eccentricity features 494 have cam contact faces 494 b which contact the lugs 208 of capper 202 during this rotation. This contact causes a lowering force on the lugs 208 which is transferred to the sprung cap 204,206 of the capper 202, thereby lowering the cap 204 and exposing the printhead for printing. The rotation is ceased once the open part 494 a of the eccentricity features 494 faces away from the position of the capper 202, as illustrated in FIG. 20B.

When printing is complete or capping is otherwise desired, the motor 482 is again operated to rotate the eccentric gears 492 until the open part 494 a of the eccentricity features 494 again faces toward the capper 202. In this position, the lugs 208, and therefore the sprung cap 204, return to the capped position.

Returning to the assembly, a printhead cartridge support 510 is positioned in the support frame 434, as illustrated in FIG. 21. The sidewalls 434 a of the support frame 434 are designed to flex to allow insertion of the printhead cartridge support 510. Once inserted, the printhead cartridge support 510 is held in the support frame 434 by the engagement of the apertured features 502 for holding the eccentric gears 492 and slotted features 512 in the printhead cartridge support 510. The printhead cartridge support 510 supports, in cooperation with the upper portion 428 of the body 402, the printhead cartridge and provides reference alignment of the printhead with respect to the cradle unit when the printhead cartridge is inserted into the cradle unit.

The printhead cartridge support 510 has spike wheels 514 (see FIG. 5) which cooperate with the exit roller 456 to assist the ejection of print media from the printhead. A print media guide 516 for guiding the print media past the printhead is also provided in the printhead cartridge support 510. The print media guide 516 includes a flexibly mounted foil 518 for providing a resilient guiding force on the leading edge of the print media transported from the media supply cartridge 600 by the drive and idler rollers 450,454 as the media enters a media slot 520 of the media guide 516 (see FIGS. 5, 6 and 21). The foil is preferably made of Mylar.

A media sensor 522 is provided in the media guide 516 (see FIG. 22) for sensing the leading and trailing edges of the print media so that printing may be accurately controlled based on the position of the print media relative to the printhead. This is achieved by the accurate positioning of the media sensor 522 in the mounted printhead cartridge support 510 which provides a fixed offset between the media sensor 522 and the first row of printhead nozzles. An offset of the order of 33 millimetres provides a sufficient delay between a sensed leading edge and start of printing. The illustrated media sensor 522 is an opto-electric transceiving sensor which emits light into the media slot 520 and senses the amount of light return. When media is in the light path, a change in the amount of light is detected.

With the printhead cartridge support 510 in place, a media transport drive arrangement is assembled on the support frame 434. This is done by fitting pulley wheels 524 onto the first ends of the drive and exit rollers 454,456, mounting a drive motor 526 with associated inertia flywheel 528 and pulley wheel 530 in a motor bay 532 of the printhead cartridge support 510, mounting a tensioner 534 to the sidewall 434 a of the support frame 434 and feeding a drive belt 536 over the pulley wheels 524,530 and tensioning it with the tensioner 534 (see FIG. 23).

The tensioned drive belt 536 transfers the driving force of the drive motor 526 to the pulley wheels 524 and therefore the drive and exit rollers 454,456. The resultant rotation of the drive and exit rollers is used and controlled to transport the print media from the media supply cartridge past the printhead of the inserted printhead cartridge and out through the printed media exit slot 414 in the body 402.

In the illustrated embodiment, the drive belt is a smooth endless belt, and the tensioner is used to provide proper operational tensioning of the smooth belt about the smooth pulley wheels. However, a corrugated or like drive belt may be used in conjunction with toothed pulley wheels.

An encoder disc 538 is fitted on the second end of the drive roller 454 and an encoder sensor 540 is mounted to the sidewall 434 a of the support frame 434 for sensing the position of the encoder disc 538 and therefore the rotational speed of the drive motor 526 (see FIGS. 5 and 24). The illustrated encoder sensor is a U-shaped opto-electric sensor which emits light through holes in the encoder disc as the disc is rotated with the drive roller.

Returning to the assembly, a media pick-up device 542 is then mounted to the support frame 434. The media pick-up device 542 comprises a media cartridge support 544 and a picker assembly 546. The media cartridge support 544 has two hook features 544 a which are slid into engagement with two apertures 434 c in the base 434 b of the support frame 434. A screw is used to secure the media cartridge support 544 to the support frame 434 (see FIG. 24). The media cartridge support 544 is provided with a ridge 544 b and details 544 c on a base 544 d thereof for facilitating the insertion of, and for supporting, the media supply cartridge 600 (see FIG. 6). The media cartridge support is preferably a plastics molding having the ridge and details.

The picker assembly 546 comprises a picker roller 548, associated gear train 550 and picker motor 552 housed in a body 554. Preferably the body 554 is a molding having a base 554 a in which the picker motor 552 is mounted and an arm 554 b in which the gear train 550 and picker roller 548 are mounted via associated shafts (see FIG. 24). The base 554 a of the picker assembly 546 is pivotally mounted to the media cartridge support 544 by engaging (molded) pins 554 c of the picker assembly body 554 with pivot details 544 b of the media cartridge support 544, as illustrated in FIGS. 25A and 25B. In this way, the picker roller is able to move in and out of contact with the media of the media supply cartridge.

The illustrated gear train 550 has five gears, including a motor gear 556 located on a shaft of the picker motor 552, a picker gear 558 located on a shaft of the picker roller 548 and three intermediate gears 560. With respect to the intermediate gears 560, the gear 560 a adjacent (i.e., closest to) the picker gear 558 is a simple gear, whereas the other two intermediate gears 560 b and 560 c are compound gears. The (compound) gear train 550 is used to transfer the rotational driving force of the picker motor 552 to the picker roller 548 so that the picker roller 548 is rotated at a predetermined rotational speed. The gear train provides a gearing ratio of 50:1 at the picker roller. The picker roller 548 comprises a grip tyre 548 a arranged on the roller shaft which grips the sheet media of the inserted media supply cartridge. The grip tyre is preferably made of rubber.

Each of the shafts of the picker and intermediate gears are flex fitted into molded details in the picker assembly body via suitable bearings for allowing rotation of the shafts. It is to be understood that more or less gears may be used in the gear train as is suitable with the rotational force delivered by the picker motor and the rotational speed required for the picker roller 548 to successfully and effectively pick-up the sheet media.

Whilst the rotation of the picker roller 548 is used to perform the picking of the sheet media, the pivoting of the picker assembly 546 is used to consistently position the picker roller 548 in contact with the sheet media as the sheet media is depleted from the inserted media supply cartridge.

In the illustrated embodiment, the picker motor 552 of the pick-up device 542 is located within this pivoting part 546 of the device. Conventionally, picker motors are located external to such a pivoting parts of a media picker. This external positioning means that a powerful, and therefore large, picker motor is required in order to deliver the necessary torque to the roller. The power and size of the picker motor is reduced by locating the picker motor closer to the roller within the pivoting part. For example, a brushed DC motor delivering a maximum torque of 2 mNm (milliNewton metres) can be used for the picker motor. Whereas a motor capable of delivering about 20% more torque is typically required for an externally positioned motor, due to drive train losses experienced in the extended drive mechanism, i.e., losses due to a longer coupling shaft and at least one or more gear reduction stages on the chassis, in addition to the usual gear coupling stage from pick-up assembly pivot to the picker roller 548.

The mounted position of the pick-up device 542 (see FIG. 6) is configured so that the picker roller 548 picks the sheet media from the inserted media supply cartridge and delivers the leading edge of the sheets to the pinch of the drive and idler rollers, which then take-up the sheets for transport past the printhead of the inserted printhead cartridge.

In order to ensure successful take-up of the sheets, the picker roller 548 is driven at a rotational speed which is less than the rotational speed of the drive roller 454. Typically, the picker roller 548 is driven at a speed about 5% lower than that of the drive roller 454. This mismatch in speed means that the take-up rollers 450,454 pull the sheets faster than the picker roller 548 is able to deliver the sheets. The pivoting action of the picker assembly 546 allows the picker roller 548 to come out of contact with the sheet being pulled by the take-up rollers 450,454 due to the picker motor not be able to match the increase in speed on the picker roller 548.

Depending on the speed of take-up, the picker roller 548 may bounce and drag on the sheets as they are being taken up due to a swinging motion of the picker assembly 546 about the pivot points 544 b,554 c. This bouncing and dragging generally has a negligible effect on the take-up of the sheets, however it may cause wear on the rubber grip tyre 548 a of the picker roller 548 and the bearings of the gear train 550, and velocity spikes in the transport of the sheets, which are undesired due to the possible effect on the print quality.

In an alternative embodiment of the picker device illustrated in FIGS. 26A and 26B, the drag of the picker roller 548 on the sheets is reduced by disengaging the picker roller 548 from the picker motor 552 during the take-up of the sheets. This is done by arranging one of the intermediate gears on a pivot arm 562 which pivots the gear out of mesh with the other gears when the rotational speed of the picker roller 548 gear increases at the delivery of the leading edge of a sheet to the take-up rollers 450,454. This disengagement allows the picker roller to effectively free wheel thereby reducing the drag on the sheets. The drag is minimised if the pivoted gear is that closest to the picker roller 548 gear due to the bearing and gear mesh friction of each additional gear not being added to the bearing friction of the picker roller 548. This arrangement is illustrated in FIGS. 26A and 26B, where the pivot arm 562 connects the shaft of the closest gear 560 a and the adjacent compound gear 560 b.

The pivoted gear 560 a is configured to be brought back into engagement with the other gears by the driving torque of the picker motor 552 once the trailing edge of the currently picked sheet has been removed by the take-up rollers 450,454.

Returning to the assembly, a connection interface 564 for the printhead cartridge 200 is mounted to the cradle unit 400. The connection interface 564 incorporates a printed circuit board 566 on which power and data connections 568 for the printhead cartridge 200 are arranged. The connection interface board 566 is mounted to the cradle unit 400 by lowering a lower edge 566 a of the connection interface board 566 into a slot 510 a of the printhead cartridge support 510 for receiving the printhead cartridge 200 (see FIGS. 6 and 27) and engaging holes 566 b in the connection interface board 566 with details 510 b within the slot 510 a (see FIG. 28). The holes 566 b are engaged with the details 510 b by tilting the connection interface 564 board against a face 510 c of the printhead cartridge slot 510 a. A tilt angle of up to 1.5 degrees may be accommodated. In this mounted position, the power and data connections 568 are exposed for connection to like connections of the inserted printhead cartridge 200, as illustrated in FIG. 6.

Print control circuitry 570 is then mounted to the body 402 of the cradle unit 400. The print control circuitry 570 incorporates a printed circuit board 572 on which a print controller 573, the power connector 406 and the data connectors 408,410 are arranged. The print control circuitry board 572 is mounted by engaging a connection header 572 a with a complementary connection header 566 c of the connection interface 564 at the exterior of one of the sidewalls 434 a of the support frame 434 and securing the board 572 with screws or the like to that sidewall (see FIGS. 29 and 30). The mating of the connection headers provides complete connection of power and data to the printhead cartridge via the connection interface.

In the illustrated embodiment, the connection header 572 a of the print control circuitry 570 is a male header and the connection header 566 c of the connection interface 564 is a female header, and the connection interface board 566 projects substantially orthogonally to the print control circuitry board. Other arrangements are possible. During this connection, slight movement of the connection interface 564 board is possible on the details 510 b within the slot 510 a since an upper edge 566 d of the connection interface board 566 is free to move. This movement facilitates the mating of the connection headers and accommodates the tilt angle of the connection interface board.

FIG. 31 is a system diagram illustrating the connections between the connection interface 564, the print control circuitry 570, the internal components of the cradle unit 400, the printhead cartridge 200, a camera connected at the PictBridge connector 410, a PC connected at the USB connector 408 and an external power supply connected at the power connector 406.

The print control circuitry board 572 has a capper sensor 574 for sensing a position of the capper (see FIG. 29). The illustrated capper sensor 574 is configured as a U-shaped opto-electric sensor through which the half-cylindrical code feature 484 is able pass as the coded gear 480 is rotated. The capper sensor emits and senses light which is uninterrupted when the code feature is in the (capped) position shown in FIG. 20A and is interrupted when the code feature is in the (uncapped) position shown in FIG. 20B.

The capper sensor 574 is used by the print control circuitry 570 to operate the capper motor 482 to position the capper out and into its capped position. The capper sensor 574 is also used to reposition the eccentricity features 494 of the eccentric gears 492 in order to correct the movement caused by the aforementioned meshing of the coded and motor gears 480 and 508 during assembly.

The print control circuitry board 572 also has connection ports 576 for connecting the capper motor 482, the drive motor 526, the encoder sensor 540, the picker motor 552 and the media sensor 522 to the power supply and print control circuitry, as illustrated in FIG. 30.

Various control buttons 578 and indicators 580, such as LEDs, for the function and control of the printer 100 are also incorporated on the print control circuitry board 572. The control buttons 578 include an on/off button and a print function button, where the print function button may be operated by a user to control functioning of the printer 100, such as media feed, reprint, creation of print effects, etc. The indicators 580 may include operation status, print status, printhead cartridge, ink volume, media supply, PC/camera connection, etc, indicators. The buttons and indicators 578,580 are positioned to locate within the control panel 418 when the upper portion 428 of the body 402 is assembled onto the support frame 434 (see FIG. 5).

The complexity of the print control circuitry 570 is minimised by arranging certain circuitry in the connection interface 564. In particular, power regulation circuitry 582 and/or power storage circuitry 584 is integrated in the connection interface 564.

The power regulation circuitry 582 regulates the supply of power from the external (or internal) power supply via the print control circuitry board 572. Such regulation is needed in order to ensure that constant and consistent power is delivered to the ink ejection nozzles of the printhead, thereby maintaining consistent print quality. In particular, the drop ejection of the printhead nozzles is a function of both the supply voltage and the firing pulse width. Each nozzle is configured to eject an ink drop having a volume of about 1.2 picolitres and a velocity of about eight metres per second. If the supply voltage varies significantly, the pulse width needs to be varied to maintain consistent drop quality. Such pulse width variation is undesired and therefore tight regulation is needed.

An exemplary power regulation circuit 582 is illustrated in FIG. 32. The illustrated regulator is a hysteretic regulator based on an LM3485 control chip, and takes an input voltage V_(IN) of 12 Volts at an input current of 2 Amps and outputs a regulated voltage V_(POS) of up to 5.5 Volts at a regulated current of 3.5 Amps to the inserted printhead. The maximum total variation in the output voltage under all load conditions is 100 milliVolts. This variation occurs due to load transients on the output capacitors and the ripple due to the hysteretic control, and is not significant enough to adversely effect the print quality.

The power storage circuitry 584 stores at least some of the power supplied from the external (or internal) power supply via the print control circuitry board 572. Such storage is desired to account for potential power shortages during operation of the printhead, thereby maintaining consistent print quality. Power storage also takes account for brief peaks in the nozzle current consumption which is dependent upon the image density and print speed of a printing operation.

An exemplary power storage circuit 584 is illustrated in FIG. 32 as part of the regulator 582. A number of output capacitors 586 and an inductor 588 are provided to store some of the energy supplied to the connection interface 564. In the illustrated storage circuitry 584, bulk energy storage of about 12 milliJoules is provided by eight 100 microFarad electrolytic (low ESR tantalum) capacitors 586 a, energy storage of about 900 microJoules for fast load transients is provided by six 10 microFarad ceramic capacitors 586 b and about 60 microJoules of energy is stored by the inductor 588, which is a 10 microHenry inductor. Further energy storage may also be provided in the printhead itself.

With the internal components of the cradle unit 400 assembled and the various connections made, the assembly is encased with the upper and lower portions 428 and 430 of the body 402, by securing the upper and lower portions to the support frame 434 with screws or the like, and the lid 404 is hingedly attached to the upper portion 428.

In order to ensure the use of a printhead cartridge which is properly configured to operate with the cradle unit 400, it is possible to arrange a key feature 490 on the cradle unit 400, as illustrated in FIGS. 33 and 34, which only allows the insertion of a printhead cartridge having a complementary key feature. Such ‘branding’ of the cradle unit 400 and printhead cartridge can be carried out after manufacture.

Media Supply Cartridge

The media supply cartridge 600 is an assembly of a sheet media support 602 and a hinged lid 604, as illustrated in FIGS. 5 and 35. The sheet media support 602 is dimensioned to support a stack of sheet media on its base 606, such as 200 sheets of 4 inch by 6 inch photo paper. The lid 606 is hinged on the media support 602 so as to facilitate filling and re-refilling of the media stack. The support and lid are preferably plastic moldings or pressed metal.

A spring 608 is located within the media support 602 for maintaining a position of the stack within the media support. In the illustrated embodiment, the spring 608 is located on one sidewall 610 of the media support 602 (see FIG. 5), however other arrangements or the use of more than one spring or other biasing means is possible.

The media supply cartridge 600 is inserted into the media supply cartridge slot 412 of the cradle unit 400 so as to locate in the media supply cartridge support 544 of the pick-up device 542. The media supply cartridge 600 is held in place by the engagement of recesses 612 in the cartridge 600 with (molded) details 544 e of the media cartridge support 544 (see FIGS. 1 and 35).

As described earlier, the ridge and details 544 b and 544 c of the media cartridge support 544 facilitate the insertion of the media supply cartridge 600. A taper of the details 544 c in conjunction with the ridge 544 b result in the media supply cartridge 600 being held at an angle with respect to the base 544 d of the cartridge support 544 (see FIG. 6). This angle on the sheet media, facilitates the pick-up of the sheets by the picker roller 548.

The lid 604 is formed to have nested openings 614. The larger opening 614 a allows unobstructed withdrawal of the sheet media from the media supply cartridge, whilst the smaller opening 614 b allows unobstructed access to the sheet media by the picker roller 548 of the pick-up device 542 when the media supply cartridge 600 is inserted in the media supply cartridge slot 412 of the cradle unit 400.

The delivery of the sheet media occurs past an inclined front face 602 a of the sheet media support 602 which is supported by a similarly inclined front face 544 f of the media cartridge support 544 (see FIG. 6). The angle of the incline is configured to assist in the picking of the sheets as the sheets are depleted from the stack and the stack height decreases. A stepped region 616 is arranged in the base 606 on the sheet media support 602 to further assist in the picking of the last few sheets of the stack.

This assistance occurs when the picker roller 548 contacts and presses against the remaining sheets causing the sheets to slightly buckle about the stepped region 616. The buckling causes the leading edge of the sheets to raise slightly, making it easier for the sheets to be driven up the inclined face 602 a to the nip of the take-up rollers 450,454 by the picker roller 548. Once the stack has been depleted, the media supply cartridge 600 can be removed from the printer 100 and replaced with a new cartridge or refilled for reinsertion.

The number of sheets remaining in a media supply cartridge is monitored by the print control circuitry 570 of the cradle unit 400. This is done by storing a count of the number of sheets fed from the cartridge as sensed by the media sensor 522 of the media guide 516 and/or storing a count of the number of sheets/pages that have been printed.

Alternatively, or in addition, if the media sensor 522 of the media guide 516 senses that a sheet has not been picked by the pick-up device 542 from the media cartridge 600, by not sensing the leading edge of the sheet, the print controller 570 may, for example, cause a media supply indicator 580 of the control panel 418 to operate and/or display of a media out message on the PC or digital camera connected to the printer 100, which indicates to a user that either the media supply cartridge is depleted, the media supply cartridge has not been inserted or the media has not been successfully picked from the cartridge and allows subsequent correction by the user.

Further, media jams can be detected by the media sensor 522 by sensing that the leading edge of a sheet has passed the sensor 522 but not the trailing edge. In such a case, the print controller 570 can respond by stopping printing and operating the drive roller 454 in the reverse direction to remove the jammed sheet. If this does not work, or alternatively, the print controller may, for example, cause a media jam indicator 580 to operate and/or display of a media jam message on the PC or digital camera connected to the printer 100, which indicates to a user that a media jam has occurred and allows subsequent correction by the user.

While the present invention has been illustrated and described with reference to exemplary embodiments thereof, various modifications will be apparent to and might readily be made by those skilled in the art without departing from the scope and spirit of the present invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but, rather, that the claims be broadly construed. 

1. A printer comprising: a sheet media transport mechanism; a pick-up roller arranged to be rotated so as to contact and pick-up sheet media from a sheet media supply and a gear assembly for communicating a driving force of a motor to the pick-up roller to rotate the pick-up roller, wherein a first gear of the gear assembly is directly coupled with a second gear of the gear assembly which is concentric with the pick-up roller, the first gear being configured to disengage from the second gear substantially at the point of delivery of a leading edge of the picked sheet media to the sheet media transport mechanism so as to cease communication of the driving force of the motor to the pick-up roller.
 2. A printer according to claim 1, wherein the gear assembly is configured to deliver a gearing ratio of 50:1 from the motor to the pick-up roller.
 3. A printer according to claim 1, wherein the motor is configured to deliver a maximum torque of 2 mNm.
 4. A printer according to claim 1, wherein the first gear re-engages with the second gear substantially at the point of a trailing edge of the picked sheet media leaving contact with the pick-up roller.
 5. A printer according to claim 4, wherein the first gear is pivotable relative to the second gear so as to disengage and re-engage therewith.
 6. A printer according to claim 1, wherein the pick-up roller incorporates a grip material for gripping the sheet media.
 7. A printer according to claim 6, wherein the grip material is rubber.
 8. A printer according to claim 7, wherein the sheet media is 100 mm by 150 mm photo paper. 